Telescopic drill rod

ABSTRACT

A telescopic drill rod has two or more rod parts disposed coaxially to one another, with the inner rod part being axially slidable relative to the outer rod part. The inner rod part by means of a coupling device comprising an abutment on the outer rod part, an abutment on the inner rod part, and a locking element. The locking element is moved into the space between the two abutments by a spring. The locking element is capable of withstanding pressure forces.

O Unlted States Patent 1191 1111 3,763,666 Tibussek [451 Oct. 9, 1973 TELESCOPIC DRILL ROD 2,671,680 3/1954 Stevens 287/58 CT 3,240,511 3/1966 8' ho tal... 285/317 [75] Invent: T'bussek Mmcbengladbach, 1,919,114 7 1933 Le nfii 287/58 CT Germmly 3,107,933 10/1963 Royster 287/58 CT [73] Assignee: Maschinen-Und Bohrgeratefabrik Alfred w'rth & Primary Examiner-Charles J. Myhre Erkleng/Rhld Germany Assistant Examiner-Randall Heald 22 Filed; No 7, 97 Attorney-Holman & Stern [21] Appl. No.: 199,408

[5 7] ABSTRACT 30 FreinAl't' P'tDta 1 N F pglca [on "on y 20 57 101 l A telescopic drill rod has two or more rod parts dismany posed coaxially to one another, with the inner rod part being axially slidable relative to the outer rod part. 64/23 285/317 The inner rod part by means of a coupling device 58 F1; .ld 23 6 4 comprising an abutment on the outer rod part an 1 e 0 abutment on the inner rod part, and a locking element. The locking element is moved into the space between the two abutments by a spring. The locking ele- [56] UNITE SEEL SES SZEI ENTS ment is capable of withstanding pressure forces. 3,171,674 3/1965 Bickel et al 285/317 7 Claims, 14 Drawing Figures 1 TELESCOPIC DRILL ROD BACKGROUND OF THE INVENTION The invention relates to telescopic drill rods comprising two or more parts disposed concentrically to one another, with the inner rod part being axially slidable in relation to the associated outer part.

PRIOR ART In a known telescopic drill rod of this kind, the extensible parts of the rod consists in each case of a piston rod and a piston the solid and annular surfaces of the latter being adapted to be acted on by a pressure medium for the purpose of respectively extending and retracting the telescopic tubes. Because of the seals required, because of the pipes which must be provided in the various parts of the rod for the pressure medium, and because of the need for accurate machining of the individual parts with a high surface quality and so on, a hydraulic telescopic rod of this kind is naturally very expensive. .Furthermore, drilling pressure can be applied with a rod of this kind only when the piston of the extended part of the rod in question is continuously loaded with corresponding hydraulic pressure.

OBJECTS AND SUMMARY OF THE INVENTION An object of the invention is to provide a telescopic drill rod which is of the simplest possible construction but which is nevertheless able to transmit drilling pressure when in the extended position. A further particular object of the invention is to enable the individual parts of the rod, while in the extended position, to be easily connected together and also easily disconnected.

The invention consists in a telescopic drill rod comprising at least two rod parts disposed coaxially to one another, at least one rod part being an inner rod part and at least one other rod part being an outer rod part, said inner rod part being axially slidable relative to said outer rod part between an extended position and a nonextended position, the improvement that: said outer rod part has a first abutment, said inner rod part has a second abutment, and the telescopic drill rod also comprises a locking element and resilient biasing means, with said locking element being suitable for transmitting pressure forces, whereby when said telescopic drill rod isin said extended position, the inner rod part is locked to the outer rod part by the locking element, which moves between said first abutment and said second abutment.

The invention makes it possible for the parts of a telescopic drill rod to be coupled together in the extended position, without further aids or additional devices, in a simple, convenient manner which is particularly suitable for practical operation, in such a manner that drilling pressure can be applied. The force for this purpose can be transmitted from a suitable element in the drilling rig used in each particular case, for example a power swivel head slidable on the drilling rig mast, to the outer rod part and from the latter to the inner rod parts. In the case of a rod having a plurality of telescopically extensible parts, a corresponding number of coupling devices are provided.

For the purpose of releasing the connection between the rod parts it is not in itself impossible for the locking element of the coupling device to be moved manually from its locking position, optionally with a suitable remote control device. The invention, however, provides more particularly forthe locking element to be shifted from its locking position into a release position, which allows the inner rod part to be pushed into the outer rod part, by means of an unlocking element which is movable by axially sliding the two rod parts in relation to one another. This constitutes an extremely favorable and practical construction.

It is convenient for the unlocking element to be slidable on one of the two rod parts between two stops which are spaced apart in the direction of the longitudinal axis of the rod, with the front stop (in the direction of extension of the rod part) forming an abutment for the locking element.

Depending on the construction of the locking element, the unlocking element may also be constructed in various ways. It is particularly advantageous for a sleeve, tube, or the like to be provided as unlocking element. In this case its cross-sectional shape can be governed by the shape of the respective rod part. Thus, the tube need not necessarily have a cylindrical crosssection, but could, for example, have a square crosssection if the rod part is square in shape.

In the simplest case, the locking element may be a boss, slide, or the like. It is, however, more convenient for a plurality of locking bolts distributed over the periphery of the rod part in question to be provided for this purpose. This results in a uniform transmission of force. In the case of rod parts of circular cross-section, it is advantageous for the locking element to be in the form of a divided ring, in which case the individual parts of this ring form the locking bolts. In the case of rod parts of polygonal cross-section, it is advantageous for each side of the cross-section to be provided with a locking bolt.

It is advantageous for the individual rod parts which are telescopically slidable in the axial direction to be so constructed that they cannot turn relative to one another, so that it will also be possible for torque to be transmitted through the rod, in order to enable it to be used for rotary drilling work. This can be achieved in a simple manner by various means, for example by forming surfaces of the rod parts which slide on one another as keyway connections or giving them a crosssectional profile differing from the circular shape. The coupling device for locking together the rod parts may, however, also be so shaped that it can at the same time also transmit torque.

The invention is further explained below by way of example with reference to the drawing, in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a three-part construction of the drill rod according to the invention, partly in elevation and partly in longitudinal section;

FIG. 2 is a section on the line 11-11 in FIG. 1, on a larger scale;

FIG. 3 is a section on the line III-III in FIG. 1, on a larger scale;

FIG. 4 shows one of the two coupling devices for the rod, in the locking position, in the form of a partial section on a larger scale compared with FIG. 1;

FIG. 5 shows the coupling device of FIG. 4 in a different position;

FIGS. 6 to 9 illustrate diagrammatically the locking of the middle rod part to the outer rod part in a threepart drill rod; and

FIGS. to 14 illustrate diagrammatically the locking of all three rod parts in a three-part drill rod.

DETAILED DESCRIPTION OF THE INVENTION The telescopic drill rod illustrated comprises an outer rod part 1, which, for example, is intended for connection to a power swivel head, a middle rod part 2 slidable therein, and an inner rod part 3 which in turn is slidable in the part 2. At the upper end of the rod part 3 is provided a rotatably mounted fork element 4 equipped with a rope pulley 5, while at the bottom end there is provided a transition element 6 with a fastening stem 6a for attaching a tool. The transition element 6 is provided with a shock-absorbing insert 7, on which a driving element 8 terminating the middle rod part 2 can be supported.

In the extended position, the inner rod part 3 can be connected to the middle rod part 2 by a coupling device K and in the extended position, the middle rod part 2 can be connected to the outer rod part 1 by a coupling device K The two coupling devices are identical in fundamental construction and in their action, so that only one of them need be explained in greater detail.

The driving element 8 detachably fastened to the bottom end of the middle rod part 2 forms at the same time part of the coupling device K and contains the latter's locking element, which in this embodiment is in the form of a divided ring 9 composed of three locking bolts 9a in the form of segments of a circular ring. Each of these locking bolts 9a is bevelled in the inward direction at its upper end and is supported on the driving element 8 by means ofa coil spring 10 which urges it radially inwards in the direction of the inner rod part 3.

Near its upper end the inner rod part 3 has a cylindrical region 11 which is bounded by two stops 12 and 13 spaced apart from one another in the longitudinal direction of the rod. Between these stops a sleeve 14, which forms an unlocking element for the coupling device K is slidable on the rod part. The sleeve 14 is bevelled at its bottom end. Its outside diameter is slightly larger than the outside diameter of the stop 12 formed by a collar.

It will be assumed that the middle rod part 2 has been pushed out of the outer rod part 1 and that the inner rod part 3 is now pushed out by slackening a rope guided over the pulley 5 or by lifting the rod parts 1 and 2. Towards the end of this relative movement the front stop 12 comes to bear against the locking bolts 9a and then pushes them outwards. As the movement continues, the sleeve 14 comes to bear against the divided ring 9, but because its outside diameter is larger than that of the stop 12 it is held fast by the ring and remains lying on it. As soon as the stop 12 has passed the locking bolts 9a, the latter are pressed inwards again by the force of the springs 10, so that they are engaged in the region 11 between the stop 12 and the sleeve 14, which is held back above the divided ring 9. When the tool rests on the bottom of the borehole, the drilling operation can now immediately be continued with, the outer rod part 1 being pressed downwards, for example, by means of a power swivel head, and also at the same time pressing downwards the middle rod part 2 coupled to it. An inwardly directed shoulder 15 on the driving element 8 now bears against the locking bolts 9a and brings them in turn to bear against the stop 12, which then forms an abutment for the locking bolts 9a. In this way the pressure force can be transmitted to the inner rod part 3. This position of the coupling device K is shown in FIG. 4.

If the tool fastened on the inner rod part 3 does not rest on the ground or on the bottom of a borehole when the inner rod part 3 is extended, a position of the two rod parts 2 and 3 as illustrated in FIG. 5 can result. In this case the stop 12 on the inner rod part 3 bears against a bounding stop 16 on the driving element 8. At the same time the sleeve 14 has been driven by the stop 13 of the inner rod part 3 and by means of this stop has been pushed into the divided ring 9 and has pressed the parts 9a of the latter outwards against the force of the springs 10. If the inner rod part 3 is now raised or if the rod parts 1 and 2 are lowered, the sleeve 14 remains in its position in the divided ring 9 until in the course of the further movement of the stop 12 it is driven by the latter and raised out of the ring. The inner rod part 3 is now simply moved a short distance downwards again, that is to say is extended, the sleeve 14, the outer diameter of which, as already mentioned, is slightly larger than the outside diameter of the stop 12, now remaining lying on the divided ring 9. The parts 9a of the ring are then pressed inwards by the spring force, so that the locking position is restored.

The connection is released very simply by moving the rod parts 2 and 3 so far apart, for example by raising the middle and outer rod parts while the inner rod part remains in position, that the locking bolts are pressed apart by the sleeve 14. The position of the parts shown in FIG. 5 is thus likewise obtained. The inner rod part 3 can now without difficulty be run in with the aid of the rope holding it, with the stop 12 lifting the sleeve 14 out of the divided ring 9 and moving it in the upward direction.

The coupling device K between the middle rod part 2 and the outer rod part 1 works in a corresponding manner. It differs from the coupling device K in that the locking element is here not a divided ring, but is formed of four individual flat locking bolts 19, which are associated with the outer surfaces of a portion of the rod which has a square cross-section. In addition, instead of a cylindrical sleeve, a tube 17 of square cross-section is here provided. Otherwise, the parts of the coupling device K corresponding to those of the coupling device K are given the same reference numerals, to which a prime accent is added in each case solely to distinguish them.

FIGS. 6 to 9 illustrate diagrammatically some phases in the extension and locking of the middle rod part 2 in a three-part telescopic rod. The latter may correspond to the construction illustrated in FIGS. 1 to 5, and is shown in FIG. 6 in the retracted position. The reference 18 here designates a power swivel head which holds the drill rod on its outer part and which in known manner is movable up and down on the mast of a drilling rig. A rope 20 acting on the fork element 5 of the inner rod part 3 is guided over a motor driven rope drum or winch in the drilling rig.

FIG. 7 shows the moment during the relative movement of the two rod parts 1 and 2 when the stop 12' has pressed apart the locking bolts 19 of the upper coupling device K while the sleeve 17 remains lying on the locking bolts 19 because of its larger outside dimensions. As the movement continues, the locking bolts 19 then assume their locking position, as shown in FIG. 8. FIG. 9 shows the drilling position in which the pressure force applied by the power swivel head 18 is transmitted from the outer rod part 1 through the coupling device K to the middle rod part 2 and thus at the same time also to the retracted inner rod part 3 which still bears against the rod part 2 FIG. shows the rod in the extended condition. The coupling device K between the inner rod part 3 and the middle rod part 2 is here situated in the same position as the other coupling device K in FIG. 7. When the outer and middle rod parts are slightly lifted by means of the power swivel head 18 or by lowering the inner rod part 3 with the aid of the rope 20, the coupling device K assumes its locking position (FIG. 11).

On further sliding of the rod parts relative to one another, the position shown in FIG. 12 is obtained, in which the upper coupling device K is in the same position as in FIG. 7. FIG. 13 shows the locking position when reached by the upper coupling device K while FIG. 14 illustrates the transmission of a pressure force from the power swivel head 18 and the outer rod part 1 through the coupling device K, to the middle rod part 2 and from the latter by way of the coupling device K to the inner rod part 3.

The rod parts 1,2,3 are connected together to be axially slidable but non-rotatable on one another, so that rotary drilling work can be carried out with the rod. For this purpose the rod parts are provided with regions or elements which engage with one another and which have a cross-section differing from the circular shape, particularly a square cross-section.

Provided that the prior art permits, all the features mentioned in the description above or illustrated in the drawing should be regarded as forming part of the invention either alone or in combination.

I claim:

1. In a telescopic drill rod comprising at least two rod parts disposed coaxially to one another, at least one rod part being an inner rod part and at least one other rod part being an outer rod part, said inner rod part being axially slidable relative to said outer rod part between an extended position and a non-extended position, the

improvement that: said outer rod part has a first abutment, said inner rod part has a second abutment, a locking element located between said rod parts, resilient means operably related to the locking element for biasing the locking element in the direction of the inner rod part, said locking element serving for transmitting pressure forces to the inner rod part, whereby when said telescopic drill rod is in said extended position, the inner rod part is locked to the outer rod part by the locking element, which moves between said first abutment and said second abutment and an unlocking element movable by the axial sliding of said at least two rod parts relative to one another, the locking element being shiftable but of its locking position into a release position permitting the insertion of the inner rod part into the outer rod part by means of said unlocking element.

2. The drill rod according to claim 1, wherein at least one of said at least two rod parts has a stop, spaced from the abutment of said at least one rod part in the longitudinal axial direction of said at least one rod part, and wherein the unlocking element is mounted on said at least one of said at least two rod parts for sliding between said stop and said abutment for the locking element in the direction of extension of said at least one rod.

3. The drill rod according to claim 2, wherein the unlocking element is a sleeve.

4. The drill rod according to claim 3, wherein the outside dimensions of the unlocking element are larger than the outside dimensions of said second abutment.

5. The drill rod according to claim 1, wherein the locking element is formed of a plurality of locking bolts distributed over the periphery of said inner rod part in question.

6. The drill rod according to claim 5, wherein the said locking element is a divided ring.

7. The drill rod according to claim 1 wherein said at least two rod parts are secured against rotation relative to one another. 

1. In a telescopic drill rod comprising at least two rod parts disposed coaxially to one another, at least one rod part being an inner rod part and at least one other rod part being an outer rod part, said inner rod part being axially slidable relative to said outer rod part between an extended position and a non-extended position, the improvement that: said outer rod part has a first abutment, said inner rod part has a second abutment, a locking element located between said rod parts, resilient means operably related to the locking element for biasing the locking element in the direction of the inner rod part, said locking element serving for transmitting pressure forces to the inner rod part, whereby when said telescopic drill rod is in said extended position, the inner rod part is locked to the outer rod part by the locking element, which moves between said first abutment and said second abutment and an unlocking element movable by the axial sliding of said at least two rod parts relative to one another, the locking element being shiftable but of its locking position into a release position permitting the insertion of the inner rod part into the outer rod part by means of said unlocking element.
 2. The drill rod according to claim 1, wherein at least one of said at least two rod parts has a stop, spaced from the abutment of said at least one rod part in the longitudinal axial direction of said at least one rod part, and wherein the unlocking element is mounted on said at least one of said at least two rod parts for sliding between said stop and said abutment for the locking element in the direction of extension of said at least one rod.
 3. The drill rod according to claim 2, wherein the unlocking element is a sleeve.
 4. The drill rod according to claim 3, wherein the outside dimensions of the unlocking element are larger than the outside dimensions of said second abutment.
 5. The drill rod according to claim 1, wherein the locking element is formed of a plurality of locking bolts distributed over the periphery of said inner rod part in question.
 6. The drill rod according to claim 5, wherein the said locking element is a divided ring.
 7. The drill rod according to claim 1 wherein said at least two rod parts are secured against rotation relative to one another. 